Tantalum spinneret and method of making same



Feb. 28, 1933.

c. H. KERK 1,899,419

TANTALUM SP-INNERE'I' AND METHOD OF MAKING SAIE Filed Nov. 26, 1929 INVENTOR.

BY W ATTORNEYJ Patented Feb. 28, 1933 UNITED STATES. PATENT- orrlcs CHARLES H. KERR, 0]? 8'1. DAVIDS, PENNSYLVANIA 'rAn'rALUu srmnnam AND METHOD OF MAKING sum Application filed November 2a, 1929. Serial m. 410,000.

for example, and the holes 5 must be accurate to much less than .0001 of o of an extrusion pumpan inch. The number of holes in the crown varies with the number of filaments of the thread which is being spun. The'solution 1s forced through the spinneret holes by means are subjected to The spinnerets, therefore,

chemicals, to pressure, and to wear incident to the extrusion of the solution, in con-- sequenceof which the life of the spinneret 1s 5 relatively short. Increase in size of the holes or distortion of the holes isvery objectionable as it results in changes in the denier of the filaments.

Heretofore it haslargely been the practice. to make the spinnerets out of the precious metals or alloys thereof, such as gold and platinum and palladium. Insofar as spin-- nerets made from these metals or alloys are unaffected by the chemicals employed, they are satisfactory. However, they are relatively soft, wear rapidly, become distorted easily, and are susceptible to damage when being cleaned. I They are also quite expensive.

It is the primary object of my invention to provide a spinneret which is free from the aforesaid objectionable characteristics, is not afiected by the chemicals employed, has long life, and is inexpensive.

To this end I propoe to make the spin nerets from the metal tantalum. Tantalum, as a practical matter, spinnerets by the dies because it does not flow and adheres to the dies .and also causes the dies to wear so rapidly that only a few spinnerets can be made to size before the dies are -'spinnerets, I

solution through which an electric current is The spinneret which t cannot be shaped in P ruined. In order to make it commercially feasible to em 10y the metal tantalum for rst treat the metal-usuall in sheet form for this purpose-so that it wil l readily flow in the dies without sticking and without shortening the life of the dies. The preferred treatment is to provide a film on the surface of the metal, this being done by immersing the metal in a mild ir'on sulphate 60 passed. Thereby anoxide forms on the sur-- face inan immeasurably fine film. The pres-, ence' of this film on the surface secures the results above set forth.

To illustrate an example of the various stages or steps in the production of the spinnerets, a sheet of drawings is appended,- and on this sheet- 4 Figure 1 illustrates in section a suitable sheet of tantalum from which the spinnerets may be stamped; and

Figures 2 to .6 inclusive illustrate a s inneret, in section, at different stages 0 its manufacture.

Referring first toFigure .1, a strip or sheet of tantalum is indicated by the. reference numeral 7. This figure also shows the oxide film at 8, formed at each side of the sheet 7 in accordance with the treatment above set forth, it being noted that the plate and the film are greatly exaggerated as to thickness for purfposes of illustration.

The rst operation in the actual production of the article includes preferably simultaneous stamping and forming of generally thimble shaped members having a substantially c 'lin. rical wall"9 and a base 10 in e spinneret holes. will utimately be drilled.

In the second die 0 ration (see Figure 3) the shape ofthe thim i le is somewhat altered by extending the cylindrical wall, asshownat 9a, and reducing the diameter thereof as well'as of the head, as shown at 10a.

As seen inFigure 4-, the next operation rovides an outturned flange 11 at the open end of the cylinder 9a. The flange is then preferably trimmed to a uniform circular shape.

In accordance with Figure 5, the succeedwe provides an upturned lip outer edge of the flange 11.

Finally,'and as viewed in Fi re 6, the spinneret is completely shaped y bending the upturned lip 12 downwardly adjacent to theremaining portion of the flange 11,

ing die operation 12 or the like at the for example, as shown at 12a.

may be drilled in the head of the thimble.

neret, after I. further discovered that a tantalum spinthe holes have been formed therein, may be hardened without distortion'or change in dimension of the spinneret or USE.

spinneret holes. Such a spinneret will withstand pressure, will wear much longer, will withstand cleaning without damage if ordinary care is exercised, is unaffected by the chemicals employed and is very much cheaper than the preciousv metal. alloys heretofore employed. A. more perfect product is ensured over a relatively'long period of To hardenthe spinnerets I subject them to heat, say from 500,to 1000 degrees Fahrenheit, preferably in the neighborhood of 850 degrees Fahrenheit. As a result of this 'treatment an oxide surface is developed which gives the desired hardness without injury to or imperfection in the perforations. The depth of the oxide is controlled by the length of time of heating. While the metal'oxidizes under conditions just pointed out, it does not oxidize at low temperatures, and hence there is no danger that further oxide will be formed under the normal conditions of use.

The metal columbium is similar to tantalum and when subjected to the treatments above given, it may also be commercially produced in the form of spinnerets and the spinnerets hardened. The scope of this invention is, therefore, to be understood as including metals or alloys of metal which are similar in nature and behaviour to tantalum. The spinnerets also may be made in the form of capillaries, instead of the thimble type, and it. is to be understood that the term spinneret is used in a broad sense.

I claim 1. The herein described spinnerets which consists in immersing a sheet composed of tantalum in an iron sulphate solution, in passing a current therethrough to form an oxide on the surface of the sheet, in stamping a spinneret from the process of making 'facturing 'a sheet and in heating the spinneret to oxidize the surface thereof. v

2. The herein described process of manufacturing a spinneret fromtanta'lum sheeting which includes the steps of immersing the sheeting in an electrol tic bath, whereby to produce an oxide coa-tmg on the surface of the sheeting, and die stamping the spinneret from the oxide coated sheeting.

3.;The herein described process of manuspinneret from tantalum sheeting which includes thesteps ofimmersing the sheeting in an electrolytic bath, whereby to produce an oxide coating on the surface of the sheeting, die stamping the spinneret from the oxide coated sheetlng, and thereafterhardening the surface of the spin-neret by heat, treatment at a temperature prefera 1y above 500Fahrenheit.

4. The method of making an article from tantalum sheeting which includes immersing the sheeting in an electrolytic bath, effecting a flow of current between the bath and the sheeting to form an oxide -film on the surface of the sheeting, and thereafter die stamping the article from the sheeting, whereby the normal tendency of the tantalum to stick in the stamping dies is substantially eliminated by virtue of the electrolytic treatment. I

5. As a new articleof manufacture, a splnneret composed of tantalum and having a multiplicity of small apertures or capillary openings therethrough, the surfaces of said capillary openings being hardened.

6. The method of manufacturing a spinneret from tantalum sheeting which includes forming a spinneret from the sheeting, drilling a multiplicity of apertures or capillary openings therethrough and thereafter hardening the surfaces f said capillary openings.

ereof I have hereunto In testimony w signed my name.

CHAS. H. KERK. 

